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LM5035x / soft stop after UVLO

Guru 29710 points
Other Parts Discussed in Thread: LM5035B, LM5025A, LM5025B, LM5025C

Hi Team,

My customer wants to know the detail difference about soft-stop between LM5035A and LM5035B.



I believe LM5035A shows the PWM duty cycle gradually fall to zero with maintaining the following relation between HO/LO and SR1/SR2 in soft-stop and LM5035A shows SR1/SR2 become Low quickly although HO/LO duty gradually fall to zero in soft-stop.
Is my understanding correct?




Best Regards,
Yaita / Japan disty

  • Kensuke-san,

    My interpretation of the datasheet is that the LM5025A will ramp down the HO/LO PWM duty cycle during soft-stop, and the SR1/2 duty cycle will ramp up during soft-stop. I assume that the dead-time between the gate drive signals will be preserved during soft-stop.

    It's unclear how the SR1/2 drive signals will behave when the SS pin has decreased low enough that the HO/LO signals disappear (i.e. duty cycle goes to zero).

    For the LM5025B, only HO/LO will ramp down during soft-stop, the SR1/2 signals will stop immediately (rely on body diode rectification during soft-stop).

    For the LM5025C, there is no soft-stop function at all.


    I will check internally to make sure my understanding is correct, and to verify what happens when on LM5025A when HO/LO duty cycle drops to zero.

    Thanks,
    Bernard
  • Hi Bernard-san,

    Thank you for always for your support.
    I will wait for your feedback.

    Best Regards,
    Yaita

  • Hi Bernard-san,

    Is there any update for your confirmation?

    Best Regards,
    Yaita

  • Hi Kensuke-san,

    Bernard's interpretation is absolutely right. For LM5035A, when HO/LO duty cycle drops to zero during soft-stop, SR1/SR2 are driven to high.

    Best Regards
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